KR102649417B1 - Improvements in and relating to lubricating compositions - Google Patents

Abstract

The present invention relates to lubricant compositions, methods for reducing low speed pre-ignition (LSPI) in direct-injection spark-ignition internal combustion engines, and the use of the lubricant compositions to reduce LSPI events in such engines. Preferably, the composition comprises a detergent package comprising a borated calcium detergent, wherein the detergent package provides a calcium content in the composition of at least 0.12% by weight based on the weight of the composition, The borated calcium detergent provides a boron content in the composition of at least 100 ppmw based on the weight of the composition. Optionally, the composition includes a first detergent comprising a calcium detergent, and a second detergent comprising a borated calcium detergent.

Description

Related improvements in lubricating compositions {IMPROVEMENTS IN AND RELATING TO LUBRICATING COMPOSITIONS}

The present invention relates to lubricating compositions. More specifically, but non-exclusively, the present invention relates to a lubricating composition for reducing the occurrence of low-speed pre-ignition (LPSI) (or low-speed pre-ignition events) in spark-ignition internal combustion engines, wherein A lubricant composition with a detergent package is used to lubricate an engine crankcase.

Market demands as well as government legislation require automakers to continually improve fuel efficiency and reduce _CO2 emissions across their engine families while maintaining performance (horsepower). Using smaller engines that deliver higher power densities, increasing boost pressure by increasing specific power using turbochargers or superchargers, and lower engine speeds By retarding the engine using higher transmission gear ratios, which allow for higher torque generation, engine manufacturers have been able to provide superior performance while reducing friction and pumping losses. However, higher torque at lower engine speeds can cause random pre-ignition in the engine at low speeds (a phenomenon known as low-speed pre-ignition or LSPI), resulting in extremely high cylinder peak pressures, which can lead to catastrophic engine failure. This has been confirmed. The possibility of LSPI prevents engine manufacturers from fully optimizing engine torque at lower engine speeds in such smaller, higher output engines.

Without wishing to be bound by any particular theory, LSPI is, at least in part, based on When in operation, it can have a 24 millisecond compression stroke) and droplets (e.g. engine oil, or engine oil, fuel and/ or mixtures of deposits). Accordingly, it would be advantageous to identify and provide lubricant compositions that are resistant to auto-ignition and thereby prevent or mitigate the occurrence of LSPI.

International Patent Application Publication No. WO2015/42337 considers the use of ash-free antioxidant additives to reduce LSPI events. International Patent Application Publication No. WO2015/42340 considers the use of metal overbased detergents to reduce LSPI events. International Patent Application Publication No. WO2015/171980 relates to a method of reducing LSPI events by providing a boron-containing compound comprising a boronated dispersant, or a mixture of a boron-containing compound and a non-borated dispersant. .

The prior art has also recognized that reducing the calcium content of lubricating oil formulations can reduce LSPI occurrence (see, for example, European Patent No. 2940110). However, detergents are often considered additives necessary to maintain base engine oil performance. Accordingly, recent efforts to provide lubricant compositions that reduce LSPI events have focused on replacing calcium detergents with alternative detergents. Nevertheless, there remains a need for lubricant compositions suitable for use in modern direct-injection spark-ignition engines that reduce the occurrence of LSPI events.

Surprisingly, the present inventors have found that, for example, when a borated calcium detergent is used in a lubricating oil composition, compared to when the crankcase is lubricated with a composition containing only (non-borated) calcium detergent, the engine It was discovered that when lubricated, it unexpectedly significantly reduces the occurrence of LSPI events in direct-injection spark-ignition internal combustion engines.

Accordingly, according to a first aspect, the present invention provides a lubricating oil composition comprising a first detergent comprising a calcium detergent and a second detergent comprising a borated calcium detergent, wherein the first and second detergents comprise: Together, they provide a calcium content in the lubricating oil composition of at least 0.12% by weight based on the weight of the lubricating oil composition, and the second detergent is at least 100 ppmw, such as at least 150 ppmw, based on the weight of the lubricating oil composition. Provides the boron content in the composition.

According to a second aspect, the present invention provides a method for reducing low-speed pre-ignition (LSPI) events in a direct-injection spark-ignition internal combustion engine, the method comprising lubricating a crankcase of the engine with a lubricant composition. wherein the composition includes a detergent package containing a borated calcium detergent, wherein the detergent package provides a calcium content in the lubricating oil composition of 0.12% by weight or more based on the weight of the lubricating oil composition, , the boronated calcium detergent provides a boron content in the lubricating oil composition of at least 100 ppmw, such as at least 150 ppmw, based on the weight of the lubricating oil composition. Optionally, the lubricating oil composition is the lubricating oil composition of the first aspect of the invention.

According to a third aspect, the invention provides the use of a detergent package comprising borated calcium detergent in a lubricating oil composition for reducing LSPI events when the composition lubricates the crankcase of a direct-injection spark-ignition internal combustion engine. Provided, wherein the detergent package provides a calcium content in the lubricating oil composition of 0.12% by weight or more based on the weight of the lubricating oil composition, and the borated calcium detergent is 100% by weight based on the weight of the lubricating oil composition. and a boron content in the lubricating oil composition of at least ppmw, such as at least 150 ppmw. Optionally, the lubricating oil composition is the lubricating oil composition of the first aspect of the invention.

In this specification, the following words and expressions, when used, have the meanings set forth below.

“Active ingredient” or “(a.i.)” refers to an additive substance that is not a diluent or solvent.

“Hydrocarbyl” generally contains only hydrogen and carbon atoms, is bonded directly to the remainder of the compound through the carbon atom, and may contain heteroatoms, provided that the heteroatoms do not inherently impair the hydrocarbyl nature of the group. refers to the chemical group of a compound.

“Oil-soluble” or “oil-dispersible” or cognate terms do not necessarily indicate that a compound or additive is soluble, soluble, miscible or suspendable in oil in any proportion. However, this means, for example, that it can be dissolved or stably dispersed in oil to a sufficient extent to exert its intended effect in the environment in which the oil is used. Additionally, additional incorporation of other additives may allow for the incorporation of higher levels of specific additives, if desired.

“Major amount” means greater than 50% by mass of the composition.

“Small amount” means less than 50% by mass of the composition.

“TBN” means total base number (mg KOHg ^-1 units) as determined by ASTM D2896.

“Phosphorus content” is measured by ASTM D5185.

The “metal content” of a lubricating oil composition or additive component, for example, the molybdenum content or the total metal content (i.e., the sum of all individual metal contents) in the lubricating oil composition is determined by ASTM D5185.

“Boron content” is measured by ASTM D5185.

“Calcium content” is measured by ASTM 4951.

“Sulfur content” is measured by ASTM D2622.

“Sulfated Ash Content” is measured by ASTM D874.

It is also understood that various ingredients, not only essential but also optimal and conventional, may react under the conditions of formulation, storage or use, and the present invention also provides products obtainable or obtained as a result of any such reaction. It will be. Additionally, it is understood that any of the upper and lower limits, ranges and ratio limits described herein may be independently combined. Additionally, the components of the present invention may be isolated or exist in mixtures and are within the scope of the present invention.

Of course, it will be understood that features described in connection with one aspect of the invention may be included in other aspects of the invention. For example, the methods of the invention may include any features described for the compositions of the invention, and vice versa.

1 diagrammatically illustrates the occurrence of LSPI events in an engine according to the method for determining the occurrence of LSPI events used in embodiments herein.

Various types of abnormal combustion in spark-ignition internal combustion engines, such as knock, extreme knock (also referred to as super-knock or mega-knock), surface ignition, and pre-ignition (ignition that occurs before spark-ignition). There are several terms for this. Extreme knock occurs in the same way as traditional knock, but with increased knock amplitude, and can be mitigated using traditional knock control methods. LSPI typically occurs at low speeds and high loads. In LSPI, the initial combustion is relatively slow and similar to normal combustion, followed by a sudden increase in combustion rate. Unlike other types of abnormal combustion, LSPI is not a runaway phenomenon. The occurrence of LSPI is difficult to predict but is often cyclical in nature.

The LSPI, when operating, has a pressure of greater than about 1,500 kPa (15 kbar), for example at an engine speed of about 1000 to about 2500 revolutions per minute (rpm), for example at an engine speed of about 1000 to about 2000 rpm. 1,800 kPa (18 bar), especially in direct-injection boosted (turbocharging or supercharging) spark-ignition (gasoline) internal combustion engines that produce braking mean effective pressure levels (peak torque) of at least about 2,000 kPa (20 bar). Most likely. As used herein, Braking Mean Effective Pressure (BMEP) is defined as the work done during an engine cycle divided by the engine sweep volume (engine torque normalized by engine displacement). The word “brake” refers to the actual torque or power available at the engine flywheel, as measured on a dynamometer. Therefore, BMEP is a measure of the useful power output of an engine.

International Patent Application Publication Nos. WO2015/171978 and WO2015/171981 disclose that lubricants containing zinc dialkyl dithiophosphate compounds and boric acid dispersants are useful in reducing LSPI events. Surprisingly, the inventors have discovered that introducing boron into lubricating oil compositions via borated calcium detergents is unexpectedly more effective in reducing LSPI events compared to introducing boron via borated dispersants. In other words, the present inventors have found that, for a lubricating oil composition having a given boron concentration, the boron content of the composition is provided primarily by boronated calcium detergent compared to an equivalent lubricating oil composition whose boron content is primarily provided by boronated dispersant. , it was found that it can be more effective in reducing the frequency of LSPI events.

The occurrence of LSPI in an engine may be due to a lubricating oil composition comprising a detergent package comprising a borated calcium detergent (e.g., wherein the detergent package contains at least 0.12% by weight of calcium in the lubricating oil composition, based on the weight of the lubricating oil composition). reduction by lubricating the crankcase with a lubricating oil composition, wherein the boronated calcium detergent provides a boron content in the lubricating oil composition of at least 100 ppmw, such as at least 150 ppmw, based on the weight of the lubricating oil composition. It turns out that it can be done. Without wishing to be bound by theory, the inventors believe that borated calcium detergents are less sensitive to LSPI than their corresponding (non-borated) calcium detergents. Optionally, the detergent package includes borated calcium detergent and calcium detergent.

More particularly, it has been found that LSPI events can be reduced by using a lubricating oil composition comprising a first detergent comprising a calcium detergent and a second detergent comprising a borated calcium detergent, wherein the first and second detergents The detergents together provide a calcium content in the lubricating oil composition of at least 0.12% by weight based on the weight of the lubricating oil composition, and the second detergent is at least 100 ppmw, such as at least 150 ppmw, based on the weight of the lubricating oil composition. Provides the boron content in the lubricating oil composition.

Optionally, the first detergent comprises a calcium detergent and comprises a calcium content of at least 2% by weight, based on the weight of the first detergent. Optionally, the second detergent comprises a borated calcium detergent and has a calcium content of at least 4% by weight, and a boron content of at least 1% by weight, such as at least 2% by weight, based on the weight of the second detergent.

Optionally, the first and second detergents together provide a calcium content in the lubricating oil composition of at least 0.14% by weight, preferably at least 0.16% by weight, for example at least 0.18% by weight, based on the weight of the lubricating oil composition. do. Optionally, the first and second detergents together are present in an amount of from 0.12% to 0.35% by weight, such as from 0.14% to 0.30% by weight, preferably from 0.16% to 0.25% by weight, e.g. Provided is a calcium content in the lubricating oil composition of, for example, 0.18% to 0.20% by weight.

Optionally, the second detergent provides a boron content in the lubricating oil composition of at least 150 ppmw, preferably at least 200 ppmw, for example at least 220 ppmw, based on the weight of the lubricating oil composition. Optionally, the second detergent is present in an amount of from 100 ppmw to 800 ppmw, optionally from 150 ppmw to 750 ppmw, such as from 180 ppmw to 700 ppmw, preferably from 220 ppmw to 650 ppmw, for example, based on the weight of the lubricating oil composition. providing a boron content in the lubricating oil composition of 250 ppmw to 500 ppmw.

A combination of borated and (non-borated) calcium detergents can be particularly effective in balancing detergent activity and LSPI reduction.

Optionally, the lubricating oil composition has a calcium content of at least 0.14% by weight, preferably at least 0.16% by weight, for example at least 0.18% by weight, based on the weight of the lubricating oil composition. Optionally, the lubricating oil composition contains 0.12% to 0.35% by weight, such as 0.14% to 0.30% by weight, preferably 0.16% to 0.25% by weight, such as 0.18% by weight, based on the weight of the lubricating oil composition. It has a calcium content of % to 0.20% by weight. Optionally, the lubricating oil composition has a boron content of at least 100 ppmw, such as at least 150 ppmw, preferably at least 200 ppmw, such as at least 250 ppmw, based on the weight of the lubricating oil composition. Optionally, the lubricating oil composition has a weight of 100 ppmw to 800 ppmw, optionally 150 ppmw to 750 ppmw, such as 180 ppmw to 700 ppmw, preferably 220 ppmw to 650 ppmw, for example It has a boron content of 250 ppmw to 500 ppmw.

Lubricating oil compositions suitable for use as passenger vehicle motor oils typically include a major amount of lubricating viscosity oil and minor amounts of performance improving additives (e.g., detergents). Conveniently, boron is introduced into the lubricating oil composition used in all aspects of the invention by means of one or more borated calcium detergents. Any borated calcium detergent would be a suitable boron source. Examples of suitable borated calcium detergents include, but are not limited to, one or more borated calcium phenate detergents, one or more borated calcium sulfonate detergents, one or more borated calcium salicylate detergents, or mixtures thereof. Includes. Preferably, the borated calcium detergent is an overbased and borated calcium detergent.

The borated calcium detergents of all aspects of the invention may be prepared by any conventional method. For example, the boricated calcium detergent may be prepared by treating calcium detergent with boric acid. Methods for making borated detergents are disclosed in U.S. Patent Nos. 3,480,548, 3,679,584, 3,829,381, 3,909,691, and 4,965,004.

Optionally, the first detergent has a calcium content of 2% to 16% by weight, such as 4% to 12% by weight, such as 6% to 10% by weight, based on the weight of the first detergent. have Optionally, the second detergent contains 4% to 16% by weight, preferably 5% to 12%, for example 6% to 10% by weight of calcium, based on the weight of the second detergent. It has content. Detergents with this calcium content may be particularly useful as lubricating oil compositions.

Optionally, the second detergent contains 1% to 10% boron, preferably 2% to 8% boron, for example 2% to 6% boron, based on the weight of the second detergent. It has content. Calcium detergents with this boron content may provide a particularly good balance between the usefulness of reducing LSPI and ease of manufacture.

Metal-containing or ash-forming detergents act both as detergents to reduce or remove deposits and as acid neutralizers or rust inhibitors, reducing wear and corrosion and extending engine life. These detergents generally contain a polar head with a long hydrophobic tail. The polar head comprises a metal salt of an acidic organic compound. The salts may contain substantially stoichiometric amounts of the metal, in which case they are typically described as normal or neutral salts and have a total base number or TBN ( can be measured according to ASTM D2896). Large amounts of metal base can be introduced by reacting excess metal compounds (e.g. hydrates or hydroxides) with acidic gases (e.g. carbon dioxide). The resulting overbased detergent contains neutralized detergent as an outer layer of metal base (eg carbonate) micelles. These overbased detergents have a TBN of 150 or higher, and typically have a TBN of 200 to 450 or higher.

Optionally, the first detergent comprises an overbased and borated calcium detergent, for example having a total base number (TBN) of at least 150, preferably at least 200. Optionally, the second detergent comprises a borated and overbased calcium detergent, for example having a TBN of at least 150, preferably at least 200. Optionally, the overbased and borated calcium detergent and/or the borated and overbased calcium detergent has a TBN of 200 to 450.

The first and second detergents are preferably used together in an amount to provide a lubricating oil composition having a TBN of about 4 to about 10 mg KOH/g, preferably about 5 to about 8 mg KOH/g. Preferably, the overbased detergent based on a metal other than calcium is present in an amount that contributes no more than 60%, such as no more than 50% or no more than 40%, of the TBN of the lubricating oil composition to which the overbased detergent contributes. Preferably, the lubricating oil composition of the present invention contains non-calcium based overbased ash-containing detergent in an amount such that the overbased detergent provides no more than about 40% of the total TBN contributed to the lubricating oil composition. Combinations of overbased calcium detergents (e.g., comprising two or more of overbased calcium phenate, overbased calcium salicylate, and overbased calcium sulfonate, or two types each having different TBNs greater than 150) (including the above calcium detergents) may be used. Preferably, the first and/or second detergent has an average of about 200 or more, such as about 200 to about 500; preferably about 250 or more, such as about 250 to about 500; More preferably it has or will have a TBN of at least about 300, such as from about 300 to about 450.

Calcium detergents that can be used in all aspects of the invention include oil-soluble neutral and overbased sulfonates of calcium, phenates, sulphated phenates, thiophosphonates, salicylates, naphthenates, and other oil-soluble carboxylates, and mixtures thereof. It will be appreciated that suitable calcium detergents may also contain other metals, especially alkali metals or alkaline earth metals, such as barium, sodium, potassium, lithium, calcium and/or magnesium. The most commonly used additional metals are magnesium and sodium, either or both of which may be present in the calcium detergent and/or the borated calcium detergent. The first and/or second detergent may comprise a combination of detergents that are overbased, neutral, or both.

Sulfonates can be prepared from sulfonic acids, which are typically obtained by sulfonation of alkyl substituted aromatic hydrocarbons, such as those obtained by fractionation of petroleum or alkylation of aromatic hydrocarbons. Examples include those obtained by alkylating benzene, xylene, naphthalene, diphenyl or their halogen derivatives such as chlorobenzene, chlorotoluene and chloronaphthalene. The alkylation can be carried out with an alkylating agent having from about 3 to more than 70 carbon atoms in the presence of a catalyst. Alkaryl sulfonates generally contain from about 9 to about 80 or more carbon atoms per alkyl substituted aromatic moiety, preferably from about 16 to about 60 carbon atoms. In a preferred embodiment of the invention, the sulfonate detergent is not obtained by alkylation of toluene. Preferred sulfonate detergents are metal salts of alkylbenzene sulfonates.

Oil-soluble sulfonates or alkaryl sulfonic acids can be neutralized with oxides, hydroxides, alkoxylates, carbonates, carboxylates, sulfides, hydrogen sulfides, nitrates, borates and ethers of metals. The amount of metal compound is selected taking into account the desired TBN of the final product, but typically ranges from about 100 to 220 mass percent (preferably at least 125 mass percent) of the stoichiometrically required amount.

Metal salts of phenols and sulfurized phenols are prepared by reaction with appropriate metal compounds (e.g. oxides or hydroxides), and the neutral or overbased products can be obtained by methods known in the art. Sulfated phenols are formed by reacting phenol with sulfur or a sulfur-containing sulfide (e.g., hydrogen sulfide, sulfur monohalide, or sulfur dihalide) to form a compound in which two or more phenols are generally crosslinked by a sulfur-containing bridge. It can be prepared by forming a product that is a mixture.

Carboxylate detergents, such as salicylates, can be prepared by reacting aromatic carboxylic acids with suitable metal compounds, such as oxides or hydroxides, and neutral or overbased products can be obtained by methods known in the art. The aromatic moiety of an aromatic carboxylic acid may contain heteroatoms such as nitrogen and oxygen. Preferably, the moiety contains only carbon atoms, more preferably the moiety contains at least 6 carbon atoms, for example benzene is a preferred moiety. The aromatic carboxylic acid may contain one or more aromatic moieties, such as one or more benzene rings fused or linked through alkylene bridges. The carboxyl moiety may be attached directly or indirectly to the aromatic moiety. Preferably the carboxylic acid group is attached directly to a carbon atom on an aromatic moiety, such as a carbon atom on a benzene ring. More preferably, the aromatic moiety also contains a second functional group, such as a hydroxy group or a sulfonate group, which may be attached directly or indirectly to a carbon atom on the aromatic moiety.

Preferred examples of aromatic carboxylic acids are salicylic acid and its sulphated derivatives, such as hydrocarbyl substituted salicylic acid and its derivatives. Processes for sulphurizing, for example, hydrocarbyl-substituted salicylic acids are known to those skilled in the art. Salicylic acid is typically prepared by carboxylation of phenoxides, for example by the Kolbe-Schmitt process, where it is generally obtained as a mixture with uncarboxylated phenol, usually in a diluent.

Preferred substituents in oil-soluble salicylic acids are alkyl substituents. In alkyl substituted salicylic acids, the alkyl group advantageously contains 5 to 100, preferably 9 to 30 and especially 14 to 20 carbon atoms. If more than one alkyl group is present, the average number of carbon atoms of all alkyl groups is preferably at least 9 to ensure adequate oil solubility.

Detergents generally useful in the formulation of the lubricating oil compositions of the present invention also include "hybrid" detergents formed with mixed surfactants, for example, U.S. Pat. No. 6,153,565; No. 6,281,179; No. 6,429,178; and phenate/salicylate, sulfonate/phenate, sulfonate/salicylate, sulfonate/phenate/salicylate as described in No. 6,429,178.

Optionally, the first detergent includes calcium phenate, calcium sulfonate and/or calcium salicylate. In one embodiment, the first detergent includes calcium salicylate. Optionally, the second detergent includes borated calcium phenate, borated calcium sulfonate, borated calcium salicylate, or mixtures thereof. In one embodiment, the second detergent comprises borated calcium salicylate. Optionally, the second detergent comprises a borated analogue of the calcium detergent of the first detergent. For example, when the first detergent contains calcium salicylate, the second detergent may contain borated calcium salicylate. For example, the boricated calcium detergent of the second detergent can be prepared by boricating the calcium detergent of the first detergent.

Optionally, the second detergent comprises calcium and boron in a ratio of 1:Z weight percent calcium to weight percent boron, based on the weight of the second detergent, wherein Z is at least 0.1, preferably at least 0.2, For example, it is 0.5 or more. Optionally, Z is 0.1 to 4, preferably 0.2 to 3, for example 0.5 to 2. This ratio can provide a particularly good balance between detergent activity and LSPI reduction.

Optionally, the first detergent and the second detergent are present in a ratio of 1:X weight percent first detergent to weight percent second detergent, based on the weight of the lubricating oil composition, wherein is 0.2 or more, for example 0.3 or more. Optionally, X is 0.1 to 10, preferably 0.2 to 5, for example 0.3 to 3.

Optionally, the first detergent comprises a plurality of calcium detergents; The second detergent includes a plurality of borated calcium detergents. Optionally, the calcium detergents of the first detergent are each independently calcium phenate, calcium sulfonate or calcium salicylate. Optionally, the borated calcium detergents of the second detergent are each independently borated calcium phenate, borated calcium sulfonate or borated calcium salicylate. Preferably, the first detergent is substantially free of any detergent that is not a calcium detergent. Preferably, the second detergent is substantially free of any detergent other than a borated calcium detergent. In other words, the first detergent may consist of one or more calcium detergents and/or the second detergent may consist of one or more borated calcium detergents. When it is stated that a detergent is substantially free of or consists of a particular type of detergent, it will be understood that the detergent may nevertheless contain trace amounts of other substances. For example, the detergent may contain trace amounts of other substances that remain throughout the manufacturing process used to make the detergent. It will be appreciated that the first detergent is not a borated detergent (in other words, the first detergent is a non-borated calcium detergent), e.g., the first detergent is substantially free of boron.

Optionally, at least 75%, such as at least 90%, such as at least 95%, or 100% of the calcium content of the lubricating oil composition is provided by the first and second detergents. Optionally, at least 50%, such as at least 75%, such as at least 90%, of the boron content of the lubricating oil composition is provided by the second detergent. When the calcium and/or boron content of the lubricating oil composition is provided primarily by the first and second detergents, the LSPI reduction properties of the detergent and the composition can be controlled particularly effectively.

Optionally, the composition may further include a third detergent. Preferably, the third detergent is substantially free of calcium and/or boron. Optionally, the third detergent includes one or more phenate, sulfonate or salicylate detergents, or mixtures thereof. The third detergent may be an overbased or neutral detergent. Optionally, the third detergent includes one or more neutral metal-containing detergents (having a TBN of less than 150). These neutral metal-based detergents may be magnesium salts or magnesium salts of other alkali or alkaline earth metals other than calcium. In all aspects of the invention, the first and second detergents may be single metal-containing detergents, in which case 100% of the metals introduced into the lubricating oil composition by the detergent are from the first and second detergents. It will be attributed to Optionally, 100% of the metal introduced into the lubricating oil composition by detergents is calcium.

The third detergent may also include an ashless (metal-free) detergent, such as the oil-soluble hydrocarbyl phenolic aldehyde condensates described in US Patent Application Publication No. 2005/0277559 A1.

Preferably, the total detergent contains 0.2 to 2.0% by mass of sulfated ash (SASH) in the lubricating oil composition, preferably 0.2 to 1.5% or 0.3 to 1.0% by mass, more preferably about 0.3 to 0.8% by mass. ) is used in an amount that provides.

Optionally, the composition comprises one or more additional additives selected from the group of dispersants, corrosion inhibitors, antioxidants, pour point depressants, anti-foaming agents, supplementary anti-wear agents, friction modifiers and viscosity modifiers.

Oils of useful lubricating viscosities in the formulation of lubricating oil compositions suitable for use in the practice of the present invention range in viscosity from light distillate mineral oils to heavy lubricants such as gasoline engine oil, mineral lubricants and heavy duty diesel oils. You can have it. Typically, the viscosity of the oil is from about 2 mm ² /sec (centistoke) to about 40 mm ² /sec, especially from about 3 mm ² /sec to about 20 mm ² /sec, most preferably, measured at 100°C. It ranges from about 9 mm ² /sec to about 17 mm ² /sec.

Natural oils include animal and vegetable oils (e.g. castor oil, lard oil); liquid petroleum oils, and hydro-refined, solvent-treated or acid-treated mineral oils of paraffinic, naphthenic and mixed paraffin-naphthenic types. Oils of lubricating viscosity derived from coal or shale also serve as useful base oils.

Synthetic lubricants include hydrocarbon oils and halo-substituted hydrocarbon oils, such as polymerized and interpolymerized olefins (e.g. polybutylene, polypropylene, propylene-isobutylene copolymer, chlorinated polybutylene, poly (1-hexene), poly(1-octene), poly(1-decene)); Alkylbenzenes (e.g., dodecylbenzene, tetradecylbenzene, dinonylbenzene, di(2-ethylhexyl)benzene); polyphenyls (e.g., biphenyls, terphenyls, alkylated polyphenols); and alkylated diphenyl ethers and alkylated diphenylsulfides, and their derivatives, analogs, and homologs.

Alkylene oxide polymers and their interpolymers and derivatives whose terminal hydroxyl groups have been modified by esterification, etherification, etc. constitute another class of known synthetic lubricants. Examples of these include polyoxyalkylene polymers prepared by polymerization of ethylene oxide or propylene oxide, and alkyl and aryl ethers of polyoxyalkylene polymers (e.g., methyl-polyisopropylene glycol ether with a molecular weight of 1000 or diphenyl ether of polyethylene glycol from 1000 to 1500); and their mono- and polycarboxylic acid esters, such as acetic acid esters of tetraethylene glycol, mixed C ₃ -C ₈ fatty acid esters and C ₁₃ oxoacid diesters.

Other suitable classes of synthetic lubricants include dicarboxylic acids, such as phthalic acid, succinic acid, alkyl and alkenyl succinic acids, maleic acid, azelaic acid, suberic acid, sebacic acid, fumaric acid, adipic acid, linoleic acid dimers; esters of malonic acids, alkylmalonic acids, alkenyl malonic acids) and various alcohols (e.g. butyl alcohol, hexyl alcohol, dodecyl alcohol, 2-ethylhexyl alcohol, ethylene glycol, diethylene glycol monoether, propylene glycol). Includes. Specific examples of such esters include dibutyl adipate, di(2-ethylhexyl) sebacate, di-n-hexyl fumarate, dioctyl sebacate, diisooctyl azelate, diisodecyl azelate, dioctyl phthalate, Didecyl phthalate, dieicosyl sebacate, 2-ethylhexyl diester of linoleic acid dimer and complex esters formed by reacting 1 mol of sebacic acid with 2 mol of tetraethylene glycol and 2 mol of 2-ethylhexanoic acid. . Synthetic oils derived from the gas-to-liquefaction process from Fischer-Tropsch synthetic hydrocarbons (commonly referred to as gas-to-liquefaction or “GTL” base oils) are also useful.

Esters useful as synthetic oils also include esters made from C ₅ to C ₁₂ monocarboxylic acids and polyols and polyol esters, such as neopentyl glycol, trimethylolpropane, pentaerythritol, dipentaerythritol and tripentaerythritol. .

silicon-based oils, such as polyalkyl-, polyaryl-, polyalkoxy- or polyaryloxysilicone oils and silicate oils, including other useful classes of synthetic lubricants, such as tetraethyl silicate, tetraisopropyl silicate, , tetra-(2-ethylhexyl) silicate, tetra-(4-methyl-2-ethylhexyl) silicate, tetra-(p-tert-butyl-phenyl) silicate, hexa-(4-methyl-2-ethylhexyl) ) includes disiloxane, poly(methyl)siloxane, and poly(methylphenyl)siloxane. Other synthetic lubricants include liquid esters of phosphorus-containing acids (e.g., tricresyl phosphate, trioctyl phosphate, diethyl ester of decylphosphonic acid) and polymeric tetrahydrofurans.

Oils of the above lubricating viscosity may include Group I, Group II, Group III, Group IV or Group V base stocks or base oil blends of such base stocks. Preferably, the oil of said lubricating viscosity is a Group II, Group III, Group IV or Group V base stock, or a mixture thereof, or a Group I base stock and one or more Group II, Group III, Group IV or Group V base stocks. It is a mixture of The base stock or base stock blend preferably has a saturates content of at least 65%, more preferably at least 75%, such as at least 85%. Preferably, the base stock or base stock blend is a Group III or higher base stock or a mixture thereof, or a mixture of a Group II base stock and a Group III or higher base stock or a mixture thereof. Most preferably, the base stock or base stock blend has a saturates content of greater than 90%. Preferably, the oil or oil blend will have a sulfur content of less than 1% by mass, preferably less than 0.6% by mass, most preferably less than 0.4% by mass, for example less than 0.3% by mass.

Preferably, the volatility of the oil or oil blend, as measured by the Noack test (ASTM D5800), is 30% by mass or less, such as about 25% by mass or less, preferably 20% by mass or less, more preferably It is 15 mass% or less, most preferably 13 mass% or less. Preferably, the viscosity index (VI) of the oil or oil blend is at least 85, preferably at least 100, and most preferably between about 105 and 200.

Definitions of base stock and base oil of the present invention are found in the American Petroleum Institute (API), "Engine Oil Licensing and Certification System", Industry Services Department, 14th Edition, December 1996, Supplement 1, December 1998. ] It is the same as confirmed in [ ]. This publication categorizes base stocks as follows:

a) Group I base stocks contain less than 90% saturates and/or more than 0.03% sulfur and have a viscosity index of not less than 80 but less than 120 using the test method specified in Table 1 below.

b) Group II base stocks contain more than 90% saturates and less than 0.03% sulfur and have a viscosity index of not less than 80 but less than 120 using the test method specified in Table I below.

c) Group III base stocks contain more than 90% saturates and less than 0.03% sulfur and have a viscosity index of more than 120 using the test method specified in Table I below.

d) Group IV base stock is polyalphaolefin (PAO).

e) Group V base stocks include all other base stocks not included in Groups I, II, III or IV.

Lubricating oil compositions of all aspects of the present invention may further include phosphorus-containing compounds.

Suitable phosphorus-containing compounds include dihydrocarbyl dithiophosphate metal salts, which are commonly used as anti-wear antioxidants. The metal may be an alkali or alkaline earth metal or aluminum, lead, tin, manganese, nickel or copper. Zinc salts are most commonly used in lubricating oils in amounts of 0.1 to 6% by weight, preferably 0.2 to 2% by weight, based on the total weight of the lubricating oil composition. It can be prepared according to known techniques by first preparing dihydrocarbyl dithiophosphoric acid (DDPA), usually by reaction of P ₂ S ₅ with one or more alcohols or phenols, and then neutralizing the formed DDPA with a zinc compound. . For example, dithiophosphoric acid can be prepared by reacting a mixture of primary and secondary alcohols. Alternatively, multiple dithiophosphoric acids can be prepared, where the hydrocarbyl group on one is entirely secondary character and the hydrocarbyl group on the other is entirely primary character. To prepare zinc salts, any basic or neutral zinc compound can be used, but oxides, hydroxides and carbonates are most commonly used. Commercial additives often contain excess zinc due to the use of excess basic zinc compounds in the neutralization reaction.

The preferred zinc dihydrocarbyl dithiophosphate is the oil-soluble salt of dihydrocarbyl dithiophosphate and can be represented by the structural formula:

where R and R' contain 1 to 18 carbon atoms, preferably 2 to 12 carbon atoms and include radicals such as alkyl, alkenyl, aryl, aryl alkyl, alkaryl and cycloaliphatic radicals. It may be the same or different hydrocarbyl radicals. Particularly preferred as the R and R' groups are alkyl groups having 2 to 8 carbon atoms. Thus, the radicals are, for example, ethyl, n-propyl, i-propyl, n-butyl, i-butyl, sec-butyl, amyl, n-hexyl, i-hexyl, n-octyl, decyl, dodecyl, 2 -Includes ethylhexyl, phenyl, butylphenyl, cyclohexyl, methylcyclopentyl, propenyl, and butenyl. To achieve oil solubility, the total number of carbon atoms (i.e., R and R') in the dithiophosphoric acid will generally be about 5 or more. Therefore, the zinc dihydrocarbyl dithiophosphate (ZDDP) may include zinc dialkyl dithiophosphate. Lubricating oil compositions useful in the practice of the present invention preferably contain ZDDP or other zinc-phosphorus compound compounds in an amount of 0.01 to 0.12% by mass phosphorus, such as 0.03 to 0.10% by mass of phosphorus, preferably 0.03 to 0.10% by mass, based on the total mass of the lubricating oil composition. will contain phosphorus in an amount introducing 0.04 to 0.08% by mass. Preferably, the lubricating oil composition of the present invention suitably has a phosphorus content of about 0.08% by mass (800 ppm) or less.

Antioxidants, also sometimes called oxidation inhibitors, increase the resistance of the composition to oxidation and may act by combining with and modifying the peroxide, making the peroxide harmless, decomposing the peroxide, or deactivating the oxidation catalyst. Oxidative deterioration can manifest itself as sludge in the lubricant, varnish-like deposits on metal surfaces, and increased viscosity.

These include radical scavengers such as sterically hindered phenols, aromatic amines, especially secondary aromatic amines with at least two aromatic (e.g. phenyl groups) groups directly attached to the nitrogen atom, and organo-copper salts); peroxide decomposers (e.g. organic sulfur and organic phosphorus additives); and multifunctional materials (e.g. zinc dihydrocarbyl dithiophosphate, which can also act as anti-wear additives).

Lubricating oil compositions in all aspects of the invention may comprise antioxidants, more preferably ashless antioxidants. Suitably, the antioxidant, if present, is an ashless aromatic amine antioxidant, an ashless phenolic antioxidant, or a combination thereof. The lubricating oil composition in all aspects of the invention may include both aromatic amines and phenolic antioxidants.

Suitably, the total amount of antioxidants (e.g. aromatic amine antioxidants, phenolic antioxidants or combinations thereof) that may be present in the lubricating oil composition is at least 0.05% by mass, preferably based on the total mass of the lubricating oil composition. It is 0.1 mass% or more, more preferably 0.2 mass% or more. Suitably, the total amount of antioxidants that may be present in the lubricating oil composition is 5.0% by mass or less, preferably 3.0% by mass or less, and even more preferably 2.5% by mass, based on the total mass of the lubricating oil composition.

Dispersants keep oil-insoluble substances in suspension resulting from oxidation during use, preventing agglomeration and precipitation of sludge or deposition on metal parts. The lubricating oil composition of the present invention includes at least one dispersant and may also include a plurality of dispersants. The dispersant or dispersants are preferably nitrogen-containing dispersants and preferably supply a total of 0.04 to 0.19% by mass, for example 0.05 to 0.18% by mass, most preferably 0.06 to 0.16% by mass of nitrogen relative to the lubricating oil composition. do.

Dispersants useful in the context of the present invention include a range of nitrogen-containing ashless (metal-free) dispersants which, when added to lubricants, are known to be effective in reducing the formation of deposits in use in gasoline and diesel engines, the particles to be dispersed. It comprises an oil-soluble polymeric long chain backbone having functional groups capable of bonding with. Typically, these dispersants have amine, amine-alcohol or amide polar moieties attached to the polymer backbone, often through bridging groups. The ashless dispersants include, for example, oil-soluble salts, esters, amino-esters, amides, imides and oxazolines of long-chain hydrocarbon-substituted mono- and poly-carboxylic acids or anhydrides thereof; Thiocarboxylate derivatives of long-chain hydrocarbons; long-chain aliphatic hydrocarbons with directly attached polyamine moieties; and Mannich condensation products formed by condensing long-chain substituted phenols with formaldehyde and polyalkylene polyamines.

In general, the mono- or di-carboxylic acid-generating moieties will each react with a nucleophilic group (amine or amide), and the number of functional groups of the polyalkenyl-substituted carboxylic acid acylating agent is the number of nucleophilic groups of the final dispersant. will decide.

The polyalkenyl moiety of the dispersant of the present invention has a number average molecular weight of 700 to 3000, preferably 950 to 3000, such as 950 to 2800, more preferably about 950 to 2500, and most preferably 950 to 2400. In one embodiment of the invention, the dispersant is a combination of a lower molecular weight dispersant (e.g., having a number average molecular weight of 700 to 1100) and a higher molecular weight dispersant (e.g., having a number average molecular weight of 1500 or more, preferably 1800 to 3000, such as 2000 to 2800, More preferably, it has a number average molecular weight of 2100 to 2500, most preferably 2150 to 2400. The molecular weight of a dispersant is usually expressed in terms of the molecular weight of the polyalkenyl moiety, because the exact molecular weight range of the dispersant depends on the type of polymer used to derive the dispersant, the number of functional groups, and the type of nucleophilic group used. This is because it depends on numerous parameters, including:

The polyalkenyl moieties that lead to the high molecular weight dispersant preferably have a narrow molecular weight distribution (MWD), also called polydispersity, determined by the ratio of weight average molecular weight (Mw) to number average molecular weight (Mn). In particular, the polymer from which the dispersant of the invention is derived has a Mw/Mn of 1.5 to 2.0, preferably 1.5 to 1.9, most preferably 1.6 to 1.8.

Suitable hydrocarbons or polymers used in forming the dispersants of the present invention include homopolymers, interpolymers or lower molecular weight hydrocarbons. One class of such polymers includes ethylene and/or one or more C ₃ to C ₂₈ alpha-olefins having the formula H ₂ C=CHR ¹ wherein R ¹ is a straight or branched chain alkyl radical of 1 to 26 carbon atoms. comprising a polymer, wherein the polymer has carbon-carbon unsaturation, preferably highly terminal ethenylidene unsaturation. Preferably, the polymer comprises an interpolymer of ethylene and one or more alpha-olefins of the above formula, wherein R ¹ is alkyl with 1 to 18 carbon atoms, preferably with 1 to 8 carbon atoms, more preferably with 1 to 8 carbon atoms. It is 1 or 2 alkyl. Accordingly, useful alpha-olefin monomers and comonomers include, for example, propylene, butene-1, hexene-1, octene-1, 4-methylpentene-1, decene-1, dodecene-1, tridecene-1, tetradecene-1, pentadecene-1, hexadecene-1, heptadecene-1, octadecene-1, nonadecene-1, and mixtures thereof (e.g., mixtures of propylene and butene-1). Examples of such polymers include propylene homopolymer, butene-1 homopolymer, ethylene-propylene copolymer, ethylene-butene-1 copolymer, propylene-butene copolymer, etc., wherein the polymer has at least some terminal and/or internal unsaturated groups. Includes. Preferred polymers include unsaturated copolymers of ethylene and propylene and ethylene and butene-1. The interpolymers of the invention may comprise small amounts, such as 0.5 to 5 mol%, of C ₄ to C ₁₈ non-conjugated diolefin comonomers. However, it is preferred that the polymers of the present invention comprise only alpha-olefin homopolymers, interpolymers of alpha-olefin comonomers, and interpolymers of ethylene and alpha-olefin comonomers. The ethylene molar content of the polymer used in the present invention preferably ranges from 0 to 80%, more preferably from 0 to 60%. When propylene and/or butene-1 are used as comonomer(s) with ethylene, the ethylene content of the copolymer is most preferably 15 to 50%, although higher or lower ethylene contents may be present.

The polymer may be reacted with an alpha-olefin monomer, a mixture of alpha-olefin monomers, or ethylene in the presence of a catalyst system comprising one or more metallocenes (e.g., cyclopentadienyl-transition metal compounds) and an alumoxane compound. It can be prepared by polymerizing a mixture comprising one or more C ₃ to C ₂₈ alpha-olefin monomers. Using this process, polymers can be provided in which at least 95% of the polymer chains contain terminal ethenylidene-type unsaturation groups. The percentage of polymer chains exhibiting terminal ethenylidene unsaturation can be determined by FTIR spectroscopic analysis, titration, or ¹³ C NMR. The latter type of interpolymer may be characterized by the structural formula poly-C(R ¹ )=CH ₂ , where R ¹ is C ₁ to C ₂₆ alkyl, preferably C ₁ to C ₁₈ alkyl, more preferably C ₁ to C ₈ alkyl, most preferably C ₁ to C ₂ alkyl, such as methyl or ethyl, and “poly” refers to a polymer chain. The chain length of the R ¹ alkyl group will vary depending on the comonomer(s) selected for use in the polymerization. A minor portion of the polymer chain may contain terminal ethenyl (i.e., vinyl) unsaturation (i.e., poly-CH=CH ₂ ), and a portion of the polymer may contain internal mono-unsaturated groups (e.g., poly-CH=CH (R ¹ ), where R ¹ is as defined above). These terminally unsaturated interpolymers can be prepared by known metallocene chemistry, and are also described in U.S. Pat. Nos. 5,498,809; No. 5,663,130; No. 5,705,577; No. 5,814,715; No. 6,022,929; and 6,030,930.

Another useful class of polymers are those made by cationic polymerization of isobutene, styrene, etc. Typical polymers of this class are used for the production of C ₄ refinery streams with a butene content of 35 to 75% by mass and an isobutene content of 30 to 60% by mass in the presence of a Lewis acid catalyst, for example aluminum trichloride or boron trifluoride. It includes polyisobutene obtained by polymerization. A preferred monomer source for preparing poly- n -butene is petroleum feed streams, such as raffinate II. Such base stocks are disclosed in the art, for example in US Pat. No. 4,952,739. Polyisobutylene is the most preferred backbone of the present invention because it is readily available by cationic polymerization from butene streams (e.g. using AlCl ₃ or BF ₃ catalysts). Because it does. The polyisobutylene generally contains residual unsaturation along the polymer chain, in the amount of about one ethylenic double bond per polymer chain. A preferred embodiment uses polyisobutylene produced from a pure isobutylene stream or a raffinate I stream to produce a reactive isobutylene polymer with terminal vinylidene olefins. Preferably, the polymer, referred to as highly reactive polyisobutylene (HR-PIB), has at least 65%, such as at least 70%, more preferably at least 80%, most preferably at least 85% of terminal vinylidene. It has content. The preparation of these polymers is described, for example, in US Pat. No. 4,152,499. HR-PIB is known and is marketed under the trade name Glissopal® (from BASF).

Polyisobutylene polymers that can be used are generally based on hydrocarbon chains of 700 to 3000. Methods for producing polyisobutylene are known. Polyisobutylene can be functionalized by halogenation (e.g., chlorination), thermal “ene” reaction, or free radical grafting using a catalyst (e.g., peroxide), as described below.

The hydrocarbon or polymer backbone is randomly distributed along the chain, for example, selectively at the carbon-carbon unsaturation sites on the polymer or hydrocarbon chain, or using any of the above three methods or a combination thereof in any order, It may be functionalized with a carboxylic acid generating moiety (preferably an acid or anhydride moiety).

Methods for reacting polymeric hydrocarbons with unsaturated carboxylic acids, anhydrides or esters and for preparing derivatives from such compounds are described in U.S. Pat. No. 3,087,936; No. 3,172,892; No. 3,215,707; No. 3,231,587; No. 3,272,746; No. 3,275,554; No. 3,381,022; No. 3,442,808; No. 3,565,804; No. 3,912,764; No. 4,110,349; No. 4,234,435; No. 5,777,025; and 5,891,953, as well as European Patent Nos. 0 382 450 B1; Disclosed in Canadian Patent No. 1,335,895 and British Patent Application No. 1,440,219. The polymer or hydrocarbon may have a functional moiety or agent (i.e., acid, anhydride, ester moiety, etc.) attached to the predominantly carbon-to-carbon unsaturation (also referred to as ethylenic or olefinic unsaturation) sites on the polymer or hydrocarbon chain. By reacting the polymer or hydrocarbon, using a halogen-assisted functionalization (e.g., chlorination) process or thermal “ene” reaction, under conditions to add, for example, a carboxylic acid producing moiety (preferably an acid or anhydride) It can be functionalized as .

Selective functionalization involves passing chlorine or bromine through the polymer at a temperature of 60 to 250° C., preferably 110 to 160° C., such as 120 to 140° C., for about 0.5 to 10 hours, preferably 1 to 7 hours. This can be achieved by halogenating (e.g., chlorination or bromination) the unsaturated α-olefin with chlorine or fluorine at about 1 to 8% by mass, preferably 3 to 7% by mass, based on the weight of the polymer or hydrocarbon. . The halogenated polymer or hydrocarbon (hereinafter “mainchain”) is then added to the main chain with the required number of functional groups such that the resulting product contains the desired number of moles of mono-unsaturated carboxylic acid reactant per mole of halogenated main chain. Add sufficient mono-unsaturated reactant and react at 100 to 250° C., generally about 180° C. to 235° C., for about 0.5 to 10 hours, such as 3 to 8 hours. Alternatively, the main chain and mono-unsaturated carboxylic acid reactants are mixed and heated while chlorine is added to the hot mass.

Chlorination typically helps to increase the reactivity of the starting olefin polymerized mono-unsaturated functionalized reactant, but may also be used in some polymers or hydrocarbons contemplated for use in the present invention, particularly preferred polymers with high end bond content and reactivity. or hydrocarbons) is not necessarily required. Therefore, preferably, the backbone and the mono-unsaturated functional reactant, such as the carboxylic acid reactant, are brought into contact at elevated temperatures to allow an initial thermal “ene” reaction to occur. The “N” reaction is known.

The hydrocarbon or polymer backbone can be functionalized by randomly attaching functional moieties along the polymer chain by a variety of methods. For example, the polymer can be grafted with mono-unsaturated carboxylic acid reactants as described above, in solution or in solid form, in the presence of a free-radical initiator. When carried out in solution, the grafting occurs at elevated temperatures ranging from about 100 to 260° C., preferably 120 to 240° C. Preferably, the free-radical initiated grafting will be achieved, for example, in a mineral lubricant solution containing 1 to 50% by mass, preferably 5 to 30% by mass, of polymer, based on the initial total oil solution. .

Free-radical initiators that can be used are peroxides, hydroperoxides, and azo compounds, preferably those that have a boiling point above about 100° C. and that thermally decompose within the grafting temperature range to give free radicals. Representative free-radical initiators are azobutyronitrile, 2,5-dimethylhex-3-en-2, 5-bis-tert-butyl peroxide and dicumene peroxide. The initiator, if used, is typically used in an amount of 0.005% to 1% by weight based on the weight of the reaction mixture solution. Typically, the mono-unsaturated carboxylic acid reactant and free-radical initiator described above are used in a weight ratio ranging from 1.0:1 to 30:1, preferably 3:1 to 6:1. The grafting is preferably carried out under an inert atmosphere, such as under nitrogen blanketing. The resulting grafted polymer is characterized by having carboxylic acid (or ester or anhydride) residues randomly attached along the polymer chain, of course being understood as part of the polymer chain remaining ungrafted. The free radical grafting described above can also be used with other polymers and hydrocarbons of the present invention.

Preferred mono-unsaturated reactants used to functionalize the main chain are mono- and di-carboxylic acid materials, i.e. acids, anhydrides or acid ester materials, such as (i) mono-unsaturated C ₄ to C ₁₀ dicarboxylic acids ( wherein (a) the carboxylic acid groups are adjacent (i.e., on adjacent carbon atoms), and (b) at least one, preferably both, of the adjacent carbon atoms are part of the mono-unsaturation; (ii) derivatives of (i), such as anhydrides or C ₁ to C ₅ alcohol-derived mono- or diesters of (i); (iii) mono-unsaturated C ₃ to C ₁₀ mono-carboxylic acids in which the carbon-carbon double bond is conjugated with a carboxylic acid group (i.e., has the structure -C=C-CO-); (iv) derivatives of (iii), such as C ₁ to C ₅ alcohol-derived mono- or diesters of (iii). Mixtures of mono-unsaturated carboxylic acid substances (i) to (iv) may also be used. The mono-unsaturated carboxylic acid reactant may become saturated upon reaction with the main chain. Thus, for example, maleic anhydride becomes main chain-substituted succinic anhydride and acrylic acid becomes main chain-substituted propionic acid. Examples of the mono-unsaturated carboxylic acid reactants include fumaric acid, itaconic acid, maleic acid, maleic anhydride, chloromaleic acid, chloromaleic anhydride, acrylic acid, methacrylic acid, crotonic acid, cinnamic acid, and lower versions of the foregoing. Alkyl (eg C ₁ to C ₄ alkyl) acid esters such as methyl maleate, ethyl fumarate and methyl fumarate.

To provide the necessary functional groups, the mono-unsaturated carboxylic acid reactant, preferably maleic anhydride, is typically present in an equimolar amount to about 100% by mass excess, preferably 5 to 50% by mass, based on mole of polymer or hydrocarbon. Amounts in the % excess range will be used. Unreacted excess mono-unsaturated carboxylic acid reactant can be removed from the final dispersant product, for example, by stripping, generally under vacuum, if necessary.

The functionalized oil-soluble polymeric hydrocarbon backbone is then derivatized with a nitrogen-containing nucleophilic reactant such as an amine, aminoalcohol, amide, or mixtures thereof to form the corresponding derivative. Amine compounds are preferred. Amine compounds useful for derivatizing functionalized polymers include one or more amines and may contain one or more additional amines or other reactive or polar groups. The amine may be a hydrocarbyl amine, or may be predominantly hydrocarbyl, wherein the hydrocarbyl group includes other groups such as hydroxy groups, alkoxy groups, amide groups, nitrile, imidazoline groups, etc. . Particularly useful amine compounds are mono- and polyamines, such as 2 to 60 nitrogen atoms per molecule, such as 1 to 12, such as 3 to 12, preferably 3 to 9, most preferably 6 to about 7 nitrogen atoms per molecule. polyalkenes and polyoxyalkylene polyamines, such as 2 to 40 (e.g., 3 to 20) total carbon atoms. Mixtures of amine compounds (e.g., those prepared by reaction of alkylene dihalides with ammonia) may be advantageously used. Preferred amines are aliphatic saturated amines such as 1,2-diaminoethane; 1,3-diaminopropane; 1,4-diaminobutane; 1,6-diaminohexane; diethylenetriamine; triethylenetetramine; polyethyleneamines such as tetraethylenepentamine; polypropyleneamines such as 1,2-propylenediamine; and di-(1,2-propylene)triamine. These polyamine mixtures (known as PAM) are commercially available. Particularly preferred polyamine mixtures are those derived by distilling the light ends from the PAM product. The resulting mixture known as “heavy” PAM or HPAM is also commercially available. The properties and properties of PAM and/or HPAM are disclosed, for example, in US Pat. No. 4,938,881; No. 4,927,551; No. 5,230,714; No. 5,241,003; No. 5,565,128; No. 5,756,431; No. 5,792,730; and 5,854,186.

Other useful amine compounds include cycloaliphatic diamines such as 1,4-di(aminomethyl) cyclohexane and heterocyclic nitrogen compounds such as imidazoline. Another useful class of amines are those described in U.S. Pat. No. 4,857,217; No. 4,956,107; No. 4,963,275; and polyamido and related amido-amines as disclosed in US Pat. No. 5,229,022. See also US Pat. No. 4,102,798; No. 4,113,639; No. 4,116,876; and tris(hydroxymethyl)aminomethane (TAM) as described in British Patent No. 989,409. Dendrimers, star amines, and amines with comb structures can also be used. Similarly, condensed amines as described in U.S. Pat. No. 5,053,152 may be used. The functionalized polymer can be reacted with the amine compound using conventional techniques as described, for example, in US Pat. Nos. 4,234,435 and 5,229,022, as well as European Patent Application No. 208,560.

A preferred dispersant composition is one comprising at least one polyalkenyl succinimide, which is a polyalkenyl substituted succinimide having a coupling ratio of 0.65 to 1.25, preferably 0.8 to 1.1, most preferably 0.9 to 1. It is the reaction product of acidic anhydride (e.g. PIBSA) and polyamine (PAM). In the context of this specification, “coupling ratio” may be defined as the ratio of the number of succinyl groups in PIBSA to the number of primary amine groups in the polyamine reactant.

Another class of high molecular weight ashless dispersants include Mannich base condensation products. Typically, the product consists of combining about 1 mole of long-chain alkyl-substituted mono- or polyhydroxy benzene with about 1 to 2.5 moles of carbonyl compound(s), as disclosed, for example, in U.S. Pat. No. 3,442,808. (e.g., formaldehyde and paraformaldehyde) and about 0.5 to 2 mol of polyalkylene polyamine. These Mannich base condensation products may include the polymer products of metallocene catalyzed polymerization as substituents for benzene groups or for succinic anhydride, in a manner similar to that described in U.S. Pat. No. 3,442,808. It may react with compounds containing the polymer. Examples of functionalized and/or derivatized olefin polymers synthesized using metallocene catalyst systems are described in the publications mentioned above.

The dispersant(s) of the invention are preferably non-polymeric (eg, mono- or bis-succinimide).

The dispersant(s) of the invention, especially lower molecular weight dispersants, may optionally be borated. These dispersants can be borated by conventional means, as generally taught in US Pat. Nos. 3,087,936, 3,254,025 and 5,430,105. Boration of the dispersant is performed by dispersing the acyl nitrogen-containing dispersant with a boron compound (e.g., boron oxide, boron halide, boric acid) in an amount sufficient to provide an atomic ratio of 0.1 to 20 for each mol of acylated nitrogen composition. , and esters of boric acid). It will be appreciated that any boron provided to the lubricating oil composition by the dispersant will also be boron provided by the detergent. Preferably, not more than 50% by weight, such as not more than 25%, such as not more than 10% by weight, of the boron in the lubricating oil composition is provided by the dispersant.

It has been found that dispersants derived from highly reactive polyisobutylene provide lubricating oil compositions with wear advantages over corresponding dispersants derived from conventional polyisobutylene. This wear advantage is particularly important in lubricants containing reduced levels of ash-containing anti-wear agents such as ZDDP. Accordingly, in one preferred embodiment, at least one dispersant used in the lubricating oil composition of the present invention is derived from highly reactive polyisobutylene.

Additional additives may be incorporated into the compositions of the present invention to enable specific performance requirements to be met. Examples of additives that may be included in the lubricating oil composition of the present invention are metal rust inhibitors, viscosity index improvers, corrosion inhibitors, oxidation inhibitors, wear modifiers, anti-foaming agents, anti-wear agents and pour point lowering agents. Some of these are discussed in more detail below.

Friction modifiers and fuel economy agents that are compatible with other components of the final oil may also be included. Examples of such substances include glyceryl monoesters of higher fatty acids, such as glyceryl monooleate; Esters of long-chain polycarboxylic acids and diols, such as butanediol esters of dimerized, unsaturated fatty acids; oxazoline compounds; and alkoxylated and alkyl-substituted mono-amines, diamines and alkyl ether amines, such as ethoxylated tallow amines and ethoxylated tallow ether amines.

The viscosity index of the base stock is increased or improved by incorporating certain polymeric materials that act as viscosity modifiers (VM) or viscosity index improvers (VII). Generally, polymeric materials useful as viscosity modifiers are polymeric materials having a number average molecular weight (M _n ) of from about 5,000 to about 250,000, preferably from about 15,000 to about 200,000, more preferably from about 20,000 to about 150,000. These viscosity modifiers can be grafted, for example, with a grafting material, such as maleic anhydride, and the grafted material can be reacted with, for example, an amine, amide, nitrogen-containing heterocyclic compound or alcohol to form a multifunctional viscosity modifier. (Dispersant-viscosity modifier) can be formed. The polymer molecular weight, especially M _n , can be determined by various known techniques. One convenient method is gel permeation chromatography (GPC), which provides additional molecular weight distribution information (WW Yau, JJ Kirkland and DD Bly, "Modern Size Exclusion Liquid Chromatography", John Wiley and Sons, New York , 1979]). Another useful method for determining molecular weight, especially for low molecular weight polymers, is the vapor pressure permeation method (see, for example, ASTM D3592).

One class of diblock copolymers useful as viscosity modifiers has been found to provide wear credence in conjunction with, for example, olefin copolymer viscosity modifiers. This wear credit is particularly important in lubricants containing reduced levels of ash-containing anti-wear agents (e.g., ZDDP). Accordingly, in one preferred embodiment, the at least one viscosity modifier used in the lubricating oil composition of the invention comprises one block and mainly (preferably predominantly) derived from vinyl aromatic hydrocarbon monomers. It is a linear diblock copolymer containing one block derived from a diene monomer. Useful vinyl aromatic hydrocarbon monomers include those containing 8 to about 16 carbon atoms, such as aryl-substituted styrene, alkoxy-substituted styrene, vinyl naphthalene, alkyl-substituted vinyl naphthalene, and the like. A polyene or diolefin contains two double bonds, usually conjugated in a 1,3 relationship. Olefins (sometimes referred to as polyenes) containing more than two double bonds are also considered to fall within the definition of “diene” as used herein. Useful dienes include 1,3-butadiene, isoprene, piperylene, methylpentadiene, phenylbutadiene, 3,4-dimethyl-1,3-hexadiene, 2,6-dimethyl- Includes those containing 4 to about 12 carbon atoms, preferably 8 to about 16 carbon atoms, such as 1,3-hexadiene, 4,5-diethyl-1,3-octadiene, 1,3-butadiene and isoprene are preferred.

“Predominantly,” as used herein with respect to a polymer block composition, means that a particular monomer or monomer type that is a major component in that polymer block is present in an amount of at least 85% by weight of that block.

Polymers made from diolefins will contain ethylenically unsaturated groups, and such polymers are preferably hydrogenated. If the polymer is to be hydrogenated, the hydrogenation may be accomplished using any technique known in the prior art. For example, the hydrogenation is carried out such that both ethylenically and aromatically unsaturated groups are converted (saturated), using methods such as those disclosed in, for example, US Pat. No. 5,251,302, US Pat. No. 3,113,986 and US Pat. The hydrogenation may be, or may be, described in U.S. Pat. No. 3,634,595; No. 3,670,054; No. 3,700,633; and U.S. Patent No. Re 27,145, conversion can be carried out selectively such that a significant portion of the ethylenically unsaturated groups are converted while little or no conversion of the aromatic unsaturated groups is performed. Either of these methods may be used to hydrogenate polymers that contain only ethylenically unsaturated groups and no aromatic unsaturated groups.

The block copolymers may include mixtures of linear diblock polymers as disclosed above with different molecular weights and/or different vinyl aromatic contents as well as mixtures of linear block copolymers with different molecular weights and/or different vinyl aromatic contents. there is. The use of two or more different polymers, when used to prepare blended engine oils, may be more desirable than a single polymer, depending on the rheological properties the product is intended to impart. Examples of commercially available styrene/hydrogenated isoprene linear diblock copolymers include Infineum SV140™, Infineum SV150™, and Infineum SV160™ (Infineum USA L.P.). USA L.P.) and Infineum UK Ltd.); Lubrizol® 7318 (available from Lubrizol Corporation); and Septon 1001™ and Septon 1020™ (available from Septon Company of America (Kuraray Group)). Suitable styrene/1,3-butadiene hydrogenated block copolymers are sold under the trade name Glissoviscal by BASF.

Pour point depressants (PPDs), also known as lubricant flow improvers (LOFIs), lower the pour point. Compared to VM, LOFI generally has a lower number average molecular weight. Like VM, LOFI can be grafted with a grafting material, for example maleic anhydride, which reacts with, for example, amines, amides, nitrogen-containing heterocyclic compounds or alcohols to produce prolific Can form soluble additives.

In the present invention, it may be necessary to include additives that maintain the viscosity stability of the blend. Accordingly, although polar group-containing additives achieve suitably low viscosity in the pre-blending step, some compositions have been observed to increase in viscosity when stored for long periods of time. Additives effective in controlling this increase in viscosity include long chain hydrocarbons functionalized by reaction with mono- or dicarboxylic acids or anhydrides used in the preparation of ashless dispersants as described above. In another preferred embodiment, the lubricating oil composition of the present invention contains an effective amount of a long chain hydrocarbon functionalized by reaction with a mono- or dicarboxylic acid or anhydride.

When the lubricating composition contains one or more of the above-mentioned additives, each additive is typically blended into the base oil in an amount that allows the additive to provide its desired function. Representative effective amounts of these additives when used in crankcase lubricants are listed below. All values listed (except detergent values) are expressed as mass percent of active ingredient (A.I.). As used herein, “A.I.” refers to an additive substance that is not a diluent or solvent.

Preferably, the Noak volatility of the fully blended lubricating oil composition (lubricating viscosity oil and all additives) will be 20% by mass or less, such as 15% by mass or less, preferably 13% by mass or less. Lubricating oil compositions useful in the practice of the present invention may have a total sulfated ash content of 0.3 to 1.2 mass %, for example 0.4 to 1.1 mass %, preferably 0.5 to 1.0 mass %.

It may be desirable, although not essential, to prepare one or more additive concentrates (sometimes referred to as additive packages) containing the additives, so that several additives can be simultaneously added to the oil to form a lubricating oil composition.

The final composition may use 5 to 25% by mass, preferably 5 to 22% by mass, typically 10 to 20% by mass of the concentrate, with the remaining amount being an oil of lubricating viscosity.

Preferably, the engine of the method of the second aspect of the invention and/or the use of the third aspect of the invention operates at an engine speed of 1,000 to 2,500 revolutions per minute (rpm), optionally 1,000 to 2,000 rpm, at 1,500 kPa. An engine that produces a braking average effective pressure level exceeding, optionally exceeding 2,000 kPa.

Preferably, the lubricating oil composition in the method of the second aspect of the invention and/or the use of the third aspect of the invention has a calcium content of at least 0.12% by weight and at least 100 ppmw, such as 150%, based on the weight of the lubricating oil composition. It has a boron content of more than ppmw. Optionally, at least 50%, preferably at least 70%, such as at least 90%, of the boron content of the lubricating oil composition is provided by the detergent package (e.g., the boronated calcium detergent). Optionally, the borated calcium detergent is present in an amount of at least 4% by weight, such as 4% to 16% by weight, preferably 5% to 12% by weight, based on the weight of the borated calcium detergent, for example Calcium content of 6% to 10% by weight, and/or at least 1% by weight, such as 1% to 10% by weight, preferably 2% to 8% by weight, for example 3% to 8% by weight. Has boron content. Optionally, the borated calcium detergent comprises borated and overbased calcium detergent and has a TBN of at least 150, preferably at least 200, for example between 200 and 450. Optionally, the borated calcium detergent includes borated calcium phenate, borated calcium sulfonate, borated calcium salicylate, or mixtures thereof. In one embodiment, the borated calcium detergent comprises borated calcium salicylate. Optionally, the borated calcium detergent comprises calcium and boron in a ratio of 1:Z weight percent calcium to weight percent boron based on the weight of the borated calcium detergent, wherein Z is at least 0.2, preferably It is more than 0.5. Optionally, the lubricating oil composition is a lubricating oil composition according to the first aspect of the invention.

The invention will be better understood by reference to the following examples (wherein, unless otherwise stated, all parts are parts by mass), which include preferred embodiments of the invention.

Description of Examples

Although the invention has been described and illustrated with reference to specific embodiments, those skilled in the art will understand that the invention is suitable for many different variations not specifically illustrated herein. By way of example only, certain possible variations will now be described.

The borated calcium detergent used in the examples below was borated calcium salicylate, prepared according to the following method. 1 kg of overbased calcium salicylate with 225 mgKOH/g of TBN and 1 kg of xylene were added to a reactor flask equipped with a Dean-Stark trap. While stirring under nitrogen, 124 g of boric acid was added slowly at room temperature. The temperature was then raised to 115°C over 2 hours and then held at 115°C for 1 hour. The reaction mixture was then heated to 140°C over 90 minutes and then held at 140°C for 40 minutes. The reaction mixture was then cooled and the mixture was centrifuged and concentrated in vacuo on a rotary evaporator to yield about 1 kg of borated calcium salicylate product. ICP analysis (measured according to ASTM D4951) showed that the product had 3.09% boron and 6.77% calcium by mass. The product had a TBN of 186 mg KOHg ^-1 (measured according to ASTM D2896).

In the examples below, data on LSPI generation were generated using a turbocharged, direct-injected GM Ecotec 2.0 liter four cylinder engine with a boost level of approximately 2,300 kPa (23 bar) at an engine speed of approximately 2000 rpm. was adjusted to produce a braking average effective pressure level of For each cycle (one cycle is two piston cycles (up/down, up/down)), data were collected with a crank angle resolution of 0.5°. Post-processing of the data included calculation of combustion metrics, verification of operating parameters within target limits, and detection of LSPI events (statistical procedures outlined below). From the above data, outliers, which are potential occurrences of LSPI, were collected. Data recorded for each LSPI cycle included peak pressure (PP), MFB02 (crank angle at 2% mass fraction combustion), other mass fractions (10%, 50%, and 90%), number of cycles, and engine cylinders. A cycle was identified as having an LSPI event if one or both of the crank angle and cylinder PP, corresponding to MFB02 of the fuel, were outliers. The outliers were determined with respect to the distribution of the particular cylinder and test segment in which they occurred. Determination of “outliers” was an iterative process involving calculating the mean and standard deviation of PP and MFB02 for each segment and cylinder, and cycles with parameters exceeding n standard deviations from the mean. The number of standard deviations, n, used as a threshold for determining outliers, is a function of the number of test cycles and was calculated using Grubb's test for outliers. Outliers were identified in the significant tail of each distribution. That is, when n is the number of standard deviations obtained from the Grubbs test for outliers, the outlier value of PP was identified as exceeding (average of peak pressure + standard deviation of n times). Likewise, outliers for MFB02 were identified as being smaller than (mean of MFB02 - standard deviation of nth round). The data was further examined to ensure that the outliers were indicative of the occurrence of LSPI rather than some other abnormal combustion event of electrical sensor failure.

An LSPI "event" is taken where there are three "normal" cycles both before and after the event. An LSPI event may contain more than one LSPI cycle or outlier. Although this method is used herein, it is not part of the invention. Studies conducted by others have counted each individual cycle, whether it was part of a multi-cycle event or not. This definition of an LSPI event is shown in Figure 1, where "1" represents a single LSPI event containing multiple LSPI cycles. The reason this is considered a single LSPI event is because each single cycle is not preceded but only followed by three normal events. “2” indicates more than 3 normal events and “3” indicates a second LSPI event comprising only a single LSPI cycle. The LSPI trigger level, denoted "4", is determined by the engine used and is related to the normal functioning of that engine.

A series of 5W-30 grade lubricant compositions representative of typical passenger car motor oils meeting GF-4 specifications were prepared. The composition of this composition is shown in Table 2 below.

In Comparative Example 1, the composition included a low boron concentration, typically 70 ppm. In Comparative Example 2, the composition contained a higher boron concentration of 250 ppm, provided by a boronated dispersant. In Example 1, the composition contained the same boron concentration as Comparative Example 2 (250 ppm), but the boron was provided by the boronated detergent. This means that the nitrogen content is closer to the nitrogen content of Comparative Example 1.

The composition was tested for occurrence of LSPI events as described above and the results are presented in Table 3 below.

Runs 1, 2, and 5 were performed on Engine 1, and Runs 3, 4, and 6 were performed on Engine 2. Run 5 using the composition of Comparative Example 2 (where additional boron is provided by the dispersant) compared to the average LSPI event frequency of Runs 1 and 2 using the composition of Comparative Example 1, which typically has lower boron concentrations, At 14%, there was a small decrease in LSPI event frequency. Run 6 using the composition of Example 1 (where additional boron was provided by the borated calcium detergent) had an average LSPI event frequency of 47% compared to the average LSPI event frequency of Runs 3 and 4 using the composition of Comparative Example 1. , showed a significant decrease in LSPI event frequency. Accordingly, the results in Table 3 show an unexpectedly large reduction in LSPI event frequency when boron is introduced into the lubricating oil composition by a borated detergent rather than a borated dispersant.

Wherever in the foregoing description integers or elements are mentioned that have known, obvious or foreseeable equivalents, such equivalents are herein incorporated by reference as if individually set forth. To determine the true scope of the invention, reference should be made to the claims, which should be construed to include any such equivalents. The reader will recognize that any integer or feature of the invention described as preferred, advantageous, convenient or similar is optional and does not limit the scope of the independent claims. Additionally, while such optional integers or features are possible advantages in some embodiments of the invention, they may be undesirable and therefore absent in other embodiments.

Claims (29)

A lubricant composition comprising a first detergent comprising a calcium detergent, a second detergent comprising a borated calcium detergent, and a third detergent having a TBN of less than 150 mg KOHg ^-1 , wherein
The first and second detergents together provide a calcium content in the lubricating oil composition of at least 0.12% by weight based on the weight of the lubricating oil composition, as measured by ASTM 4951,
Wherein the second detergent provides a boron content in the lubricating oil composition of at least 100 ppmw by weight of the lubricating oil composition, as measured by ASTM D5185. According to claim 1,
The first detergent has a calcium content of 2% to 16% by weight, based on the weight of the first detergent, and/or
A lubricating oil composition, wherein the second detergent has a calcium content of 4% to 16% by weight, based on the weight of the second detergent. According to claim 1,
The first detergent has a calcium content of 4% to 10% by weight, based on the weight of the first detergent, and/or
A lubricating oil composition, wherein the second detergent has a calcium content of 5% to 10% by weight, based on the weight of the second detergent. According to claim 1,
A lubricating oil composition, wherein the second detergent has a boron content of 1% to 10% by weight, based on the weight of the second detergent. According to claim 2,
A lubricating oil composition, wherein the second detergent has a boron content of 1% to 10% by weight, based on the weight of the second detergent. According to claim 3,
A lubricating oil composition, wherein the second detergent has a boron content of 1% to 10% by weight, based on the weight of the second detergent. According to claim 4,
A lubricating oil composition, wherein the second detergent has a boron content of 2% to 8% by weight, based on the weight of the second detergent. According to claim 1,
The lubricating oil composition, wherein the first and second detergents together provide a calcium content in the lubricating oil composition of at least 0.14% by weight, based on the weight of the lubricating oil composition. According to claim 8,
The lubricating oil composition, wherein the first and second detergents together provide a calcium content in the lubricating oil composition of at least 0.16% by weight, based on the weight of the lubricating oil composition. According to claim 1,
The lubricating oil composition of claim 1, wherein the second detergent provides a boron content in the lubricating oil composition of at least 150 ppmw, based on the weight of the lubricating oil composition. According to claim 10,
The lubricating oil composition of claim 1, wherein the second detergent provides a boron content in the lubricating oil composition of at least 180 ppmw, based on the weight of the lubricating oil composition. According to claim 1,
wherein the first detergent comprises calcium phenate, calcium sulfonate and/or calcium salicylate,
A lubricant composition according to claim 1, wherein the second detergent comprises borated calcium phenate, borated calcium sulfonate, and/or borated calcium salicylate. According to claim 12,
wherein the first detergent comprises calcium sulfonate and/or calcium salicylate,
A lubricant composition according to claim 1, wherein the second detergent comprises borated calcium sulfonate and/or borated calcium salicylate. According to claim 1,
A lubricating oil composition, wherein the second detergent comprises a borated analog of the calcium detergent of the first detergent. According to claim 1,
A lubricating oil composition, wherein the second detergent comprises calcium and boron in a ratio of 1:Z weight percent calcium to weight percent boron, based on the weight of the second detergent, where Z is at least 0.1. According to claim 15,
A lubricating oil composition wherein Z is 0.1 to 4. According to claim 15,
A lubricating oil composition wherein Z is 0.2 to 3. According to claim 1,
The lubricating oil composition, wherein the first detergent and the second detergent are present in a ratio of 1:X weight percent of the first detergent to weight percent of the second detergent, based on the weight of the lubricating oil composition, wherein According to claim 18,
A lubricating oil composition wherein X is from 0.1 to 10. According to claim 18,
A lubricating oil composition wherein X is 0.2 to 5. According to claim 1,
A lubricating oil composition, wherein at least 50% of the boron content of the lubricating oil composition is provided by the second detergent. According to claim 21,
A lubricating oil composition, wherein at least 75% of the boron content of the lubricating oil composition is provided by the second detergent. According to claim 21,
A lubricating oil composition, wherein 100% of the boron content in the lubricating oil composition is provided by the second detergent. A method for reducing low speed pre-ignition (LSPI) events in a direct-injection spark-ignition internal combustion engine comprising lubricating the crankcase of the engine with a lubricating oil composition according to any one of claims 1 to 23. According to claim 24,
In operation, the engine produces a brake average effective pressure level of greater than 1,500 kPa at an engine speed of 1,000 to 2,500 revolutions per minute (rpm). According to claim 25,
In operation, the engine produces a braking average effective pressure level of greater than 2,000 kPa. According to claim 24,
The method of claim 1, wherein the borated calcium detergent comprises a borated and overbased calcium detergent and has a TBN of at least 150 as measured by ASTM D2896. According to claim 24,
The method of claim 1, wherein the borated calcium detergent comprises a borated and overbased calcium detergent and has a TBN of at least 250 as measured by ASTM D2896. According to claim 24,
The method of claim 1, wherein the first detergent is a non-borated calcium detergent.

Images